Oral and Poster Presentations

Titles and abstracts of papers to be presented at the 4th ESO CCD Workshop


James Beletic & Reinhold Dorn



Observatory Plans, Space based Systems & Special Projects


CCD Plans of Subaru Telescope


Subaru has three optical instruments; Suprime-Cam (wide field camera for the prime focus), FOCAS (multi-slit spectrograph) and HDS (high dispersion echelle spectrograph). NAOJ (National Astronomical Observatory of Japan) CCD detector lab is responsible for supplying appropriate CCDs with these instruments. We took part in a MIT/UH consortium several years ago and had expected that MIT's device would satisfy our requirement. Slight delay of the delivery of the devices makes us to obtain other brands of CCDs including SITe and EEV. We measured the characteristics of these devices and distribute them based on the result. HDS took EEV device because they prefer blue response to red one. FOCAS relative prefer red response so they took SITe one. Suprime-Cam took the rest of devices (Four SITe and two MIT preliminary devices from phase 1).

The Suprime-Cam saw the first light in January 1999 as one of first light instrument of Subaru. The first light occurred at CAS focus and then the camera is moving to the prime focus in July 1999. Before the first light at the prime we have newly installed two more MIT devices from phase two. Apparently we are not satisfied with our devices on the camera because (1) we are not able to clock SITe device fast (2) Two MIT devices from the phase one has poor blue response and QE non-uniformity. In addition because image quality of Subaru is more than we have expected, the sampling of the camera (0''.18/pix 1pix=15um) is coarse. Smaller pixel devices are required. We start discussion with Hamamatsu Photonics about building 3k6k (12um) device which has broad band QE response (say, SITe like).

In the talk, we will present these topics and future plans of our observatory including collaborative works with Hamamatsu.


The Optical Detector Systems of ESO - Present and Future

This paper presents an overview of the optical detector systems of the European Southern Observatory


CCDs for the Rosetta Science Imaging System OSIRIS.



Backside illuminated 2k x 2k CCDs with antiblooming manufactured by EEV have been selected for the ESA Rosetta mission to comet Wirtanen. Low noise high dynamic read out electronics are developed to take full advantage of these devices. A short overview of the project status is given. The question of storage and protection against radiation damage during cruise (from 2003 to 2011) and operations at the comet will be discussed in detail in order to receive advice from the audience.


COROT Mission


COnvection and ROTation (COROT) photometer is developed in France, by Laboratoire d'Astronomie Spatiale of Marseille (LAS), Dipartement de Recherché Spatiale (DESPA) of Paris Observatory and Institut d'Astrophysique Spatiale (IAS) of Paris XI University. Several European countries contribute : Spain, Austria and SSD/ESTEC. This project is one of the PROTEUS missions of French National Space Agency (CNES). Launch is scheduled for mi-2003.

COROT has two independent scientific objectives (both requiring very long uninterrupted observations of the same stars with very high photometry accuracy) :

* Astero-seismology channel : stellar seismology is the original and primary objective, and defines the characteristics of the instrument. Seismology from the ground has already provided many important results. Limitations of this approach are essentially meteorological instabilities for photometry, lack of photons and broadening of spectral lines due to rotation for spectroscopy. Seismology from space is much less limited, as photometry at a very high accuracy on long uninterrupted observing runs is possible. In Fourier space, frequency resolution is the inverse of total duration of observation. Basic principle relies on ability to detect a periodic oscillation in a noisy signal and to measure its main parameters (frequency, amplitude and lifetime) with a certain accuracy. These values allow to know density and nature of gas but also characteristics of transport process and internal rotation. Program will measure periodic variations of luminosity from 3 hours to 1 minute. Stellar relative variations detected shall be of 2.10-6. Such amplitude give a signal to noise of 4 in Fourier space with 5 continuous observing days and 1012 photo-electrons.

* Exoplanets channel : the secondary objective is the search for transits of extraterrestrial planets over the disk of their parent star. To do this, it observes during the central program of seismology, in a neighbouring region of the sky. It will follow 3000 objects simultaneously down to magnitude 16, with a time exposure of 15 minutes (co-added frames), producing light curves of more than 30 000 stars, with an accuracy of 104 to 103 for faintest ones. A prism will favour telluric planets detection (surface temperature ~ 300 K). Today, telluric planets are only detectable by this technique Corot will observe transits with a lifetime from 3 hours to 10 hours with a periodicity from 4 days to 50 days. Amplitude of detected variation is from 10-3 to 10-4. For detection, we need 108 photo-electrons during 0.5 hour. Telescope design is strongly constrained by the need to minimize straylight from earth entering into telescope. Best protection is reached with an off-axis afocal parabolic system. Light is collected by an f/4 telescope of 27 cm entrance pupil to achieve a FOV of 2.80 x 2.80. Observations will be made without shutter. This instrument will work with 4 EEV 42-80 AIMO Back Illuminated Frame Transfert CCDs to record defocused images in order to obtain a very good relative photometric precision :

Channel Astero-seismology Exo-planets

Number of CCDs 2 2

Number of stars per CCD 6 3000

Stars defocused 300 pixels 40 pixels

Integration time 1 s 30 s

Readout mode Windowing of store section

Whole readout of store section and soft windowing CCD operating temperature will be -400C.

Platform PROTEUS, which has to be used for that mission accepts only low earth orbits. Fortunately, with a quasi-polar inertial orbit, observing runs to 150 days are possible, on selected regions of sky. COROT payload will have a weight of 85 kg and a power dissipation of 100 Watts. The lifetime of instrument on quasi-polar orbit of 800 km, is defined for at least 2.5 years.


Mosaic Projects





WFI the 8Kx8K CCD Mosaic at ESO, and the plans for the 16Kx16K.

To be supplied


Performances of the CFH12K MIT/LL-CCID20 CCDs


The CFH12K focal plane, a close-packed CCD mosaic array of 12 thinned 2K4K MIT Lincoln Laboratories CCID20 devices ran by two SDSU Generation II controllers, saw first light on the sky at the prime focus of the Canada-France-Hawaii Telescope early 1999. The first part of this article presents the results of the CCD optimization in laboratory where all the devices have been optimized at once within the CFH12K cryostat. The second part of the article focuses on the characterization and performances of the camera on the sky.


CFH12k: 12k x 8k CCD Mosaic Camera for the CFHT Prime Focus


The CFH12K is a 12k x 8k CCD mosaic camera for the Canada-France-Hawaii 3.6m telescope (CFHT) located on Mauna Kea, Hawaii. The CFH12k is comprised of 12 2k x 4k thinned backside-illuminated Lincoln Lab CCDs, arranged in a close-packed array of 2 rows each containing 6 CCDs. Located at the CFHT Prime Focus (f/4.2), the CFH12K provides a 42 by 28 arcminute field-of-view, 0.206 arcsecond per pixel sampling, with a resulting data file of more than 200Mbytes per image. The camera has been designed to exploit the exceptional wide-field imaging capability provided by the CFHT. At the time of it s commissioning in January 1999, the CFH12K is the largest thinned close-packed CCD array in astronomy. This paper describes the system architecture, and some of the relevant issues associated with the construction, evaluation, and operation of very large mosaic cameras.


Focal plane array design for the GAIA Space Mission


GAIA (Global Astrometric Interferometer for Astrophysics) is one of the candidate mission for the 5th Cornerstone of the ESA Horizon 2000 programme.

It is a high precision instrument dedicated to the global astrometric measurement of tens of millions of celestial objects at the 10 microarcsec level.

The nominal launch date is planned for 2009 and observations will be performed from L2 location. In the frame of an advance technology study, conducted by Matra Marconi Space for ESA, MMS have defined a feasible instrumental concept which shall be able to fulfil the mission requirements. The detection function is based on a large focal plane paved with hundreds of large and high electro-optics performances CCDs operated in TDI mode. The GAIA focal plane is undoubtedly one of the most challenging focal plane which should be developed in the near future for space applications. Its detailed concept will be presented during this talk. In addition, preliminary architecture of two other focal planes integrated in Gaia payload, one dedicated to spectroscopy and the second one to broadband photometry, will also be presented.


Mosaicing of CCDs for the Subaru Wide field camera (Suprime-Cam)


We are mosaicing 4096x2048 CCDs for Suprime-Cam (SUbaru PRIME focus CAMera), which is attached at the prime focus of 8.2m Subaru Telescope, The focal plane is only 30 micron, because F-ratio of the prime focus is fast(F/2). Thus, we require that the differences between the focal plane and the surfaces of CCDs be less than 15 micron considering errors in the other optical elements. To satisfy this requirement, we develop the method of placing CCDs with a high-precision described below.

1. Measure the tilt of the surfaces of CCDs using a high precision laser-displacement meter.

2. Put thin metal foil of appropriate thickness (5-300 micron) at the four corners of

individual spacers, which are jigs to place a CCD on a cold plate, so that the distance to

any point on the CCD surfaces from a common, fiducial plane, which is parallel to the cold

plate, be less than 15 micron.

3. Glue each CCD package to a spacer.

4. Install the CCD package on the cold plate.

As a result, the differences between the focal plane and the surfaces of eight CCDs are less than 10 micron, except for a small area in a corner of one CCD. For X-Y alignment, we achieve the positioning accuracy of less than 20 micron by using alignment pins, which are fixed at each spacer. We talk about details of our technique of placing CCDs with a high-precision.


CCD Manufacturers


CCD Imager Developments at Lincoln Laboratories

To be supplied

Jorden, Holtom & Pool

'Latest EEV CCD developments, and technologies for scientific CCDs'

To be supplied


Fully depleted Backside Illuminated active pixel sensors - from the infrared to X-rays

An active pixel sensor (APS) based on the Depleted P-channel junction Field Effect Transistor (DEPFET) concept will be presented. It comprises a parallel multichannel readout, low noise at high speed readout, backside illumination and a fill factor of 100%. The depleted thickness can be chosen between several tens of microns up to 500 microns. The fabrication techniques are related to the high resistivity process of the X-ray pn-CCDs. Primary applications are X-ray imaging and spectroscopy (XEUS), real-time digital autoradiography (BIOSCOPE) and in the near infrared (adaptive optics). Those applications require a frame time of 1ms of a 256x256 large device with a noise floor below 5 electrons (rms).

DEPFETs matrices with pixel geometries of 50x50 m m2 and 75x75 m m2 have already been built in formats of 64x64 pixels. JFET-CMOS front-end electronics was developed for the control and readout of the system.

First measurements will be shown to demonstrate all functional principles. The devices have been parameterized in terms of dc - characteristics, system behaviour and quantum efficiency.

Potential extensions of the already realized structures are a non-destructive repetitive readout of the signal charges and an additional analog image storage for several frames. These concepts will be presented.

Strüder & Von Zanthier

High speed pn-CCDs as wave front sensors for adaptive optics systems


Fully depleted silcon pn-CCDs with an active thickness of 300m m exhibit a quantum efficiency of 90% at a wave length of 1m m in the near infrared. The multiparallel readout architecture allows for a frame time shorter than 2ms for a device having a format of 256x256 pixels. It can be operated in a full frame mode and in a frame store mode. The pixel size is 50x50 m m2. The active area is then 2.8x2.8mm2. Cooled down to –90° C the electronic noise floor is below 5 electrons (rms).

A camera system with comparable specifications -- except for the pixel size -- was already fabricated for ESA's XMM mission, being launched in early December this year. It is foreseen to develop a data acquisition system being able to handle the desired data rate of up to 60 Megapixel per second with a dynamic range of 12 bit. The detector is supposed to operate as a wave front sensor in adaptive optics systems. The high speed, low noise and high quantum efficiency at longer wavelength offers additional sensitivity for on-line wave front corrections. Future work includes the extension of the active area to 1000x1000 pixels, monolithically fabricated on a high resistivity 6 inch silicon wafer. The main driver for this development is the planned XEUS mission, to be launched at the end of the next decade.


Characterization results for back-illuminated totally-depleted thick CCDs


Charge-coupled devices (CCDs) of novel design have been fabricated in-house at Lawrence Berkeley National Laboratory (LBNL), and the first large-format science-grade chips for astronomical imaging are now being characterized at Lick Observatory. They are made on 300-$\mu$m thick n-type high-resistivity ($\sim$10,000~$\Omega$-cm) silicon wafers, using technology developed at LBNL to fabricate low-leakage silicon microstrip detectors for high-energy physics. A bias voltage applied via a transparent contact on the back side fully depletes the substrate, making the entire volume photosensitive. The electric field also ensures that charge reaches the potential wells with minimal lateral diffusion; the PSF is as small or smaller than that obtained with normal thinned CCDs, where the field cannot be permitted to reach the rear surface. The development of a thin, transparent back side contact compatible with fully depleted operation permits blue response about the same as the best obtained with thinned CCDs, but since the entire region is active, high quantum efficiency is maintained to nearly $\lambda= 1000$~nm, above which the silicon bandgap effectively truncates production. Early characterization results indicate a charge transfer efficiency $>0.999995$, readout noise 4 e's at $-132^\circ$~C, full well capacity $>300,000\;$e's, and quantum efficiency $>85\%$ at $\lambda = 900$~nm ($>65\%$ at $\lambda = 1000$~nm). See http://ccd.lbl.gov.


Large-Scale High Resistivitiy CCDs


We present the latest results on backside illuminated CCDs fabricated on very high resistivity silicon. These devices are fabricated at Lawrence Berkeley National Laboratory and tested at UCO/Lick Observatory. Devices up to 2048x2048 (15 um pixel) devices have be fabricated and tested as. We present both laboratory characterizations of performance as well as the latest tests at the telescope.


Development of backside-thinned 4096x4096 CCD with Low-Noise Outputs

LMFS is currently developing a backside-thinned version of its successful CCD 485 4k CCD imager. This sensor will incorporate a new low noise amplifier design, which has been verified to generate less than 3 electron readout noise. Details about his exciting development program will be reviewed.


Characterization of CCDs for the DEIMOS Project

Orbit 4kx2k CCDs are being tested in the Lick Observatory labs for use in the mosaic for the DEIMOS instrument that will used at Mauna Kea. These devices are being tested in tandem to check for chip crosstalk, and CTE vs. readout speed. Our system consists of a Leach II controller running VXWorks. Details of the system and the characterization process will be detailed.


Special Techniques


Image centering accuracy with CCDs


Accurate measurement of the position of celestial objects is a fundamental step for several astrophysical investigations; for ground based instruments the atmosphere is the basic limiting factor. In space, the instrumental parameters knowledge and/or stability is potentially an issue. We implemented a very simple setup aimed at assessing the location accuracy of a CCD camera, by evaluation of the measure repeatability throughout a set of images of a

simulated stellar field. Our experiment provided a location dispersion of the order of 1/100 of the CCD pixel size, with clear evidence of dominant systematic effects. Removing such terms, in data reduction phase, we achieve a final location accuracy of 1/600 in pixel units. The limiting factor appear to be the structural stability of the set-up and above all the thermal control of the CCD camera head, providing geometric variation of the detector and therefore inducing apparent changes in the target position over the image set.

Cumani & Mantel

Phase resolved high speed photometry and spectrophotometry of Pulsars with the ESO FIERA CCD Controller



Can we do Astronomy that requires flat fielding CCDs to 1 part in 10,000?

I will discuss our attempts to do deep imaging to obtain surface photometry 10 magnitudes fainter than sky? How do you optimize a CCD to work at that level? What we have learned, it does not yet work for thinned CCDs, it used to work with a thick CCD.


Design Concepts for the Solar fine structure Imager by use of Split-Transfer CCDs


About 12 large format CCD cameras/magnetographs for imaging the fine structures of the solar surface will be attached to a 1-meter solar telescope and 4 EUV telescopes. To avoid using mechanical shutters which may cause unreliabilities under the heavy duty and harsh environments, split-transfer CCDs were selected. This contribution describes the design concepts of the cameras by use of those split-transfer chips to as well as some recent experience obtained from preliminary experiments. In addition the scientific requirements to be meet by those cameras are briefly outlined.

A new CCD for Curvature Wavefront Sensing


CCD Controllers


SciMeasure Wavefront Sensor Cameras and their Application in the Mt Palomar Adaptive Optics System.


SciMeasure, in collaboration with Emory University and Jet Propulsion Laboratory, has developed a very versatile CCD controller for use in adaptive optics, optical interferometry, and other applications requiring high speed readout rates and/or low read noise. The overall architecture of this controller system will be discussed and its performance using both EEV CCD39 and MIT/LL CCID-19 detectors will be presented. This controller is used in the adaptive optics system, developed by JPL, for the 200" Hale telescope at Palomar Mountain. Early diffraction-limited science results, recently achieved by the AO system, will also be presented.

We gratefully acknowledge the financial support of NASA through SBIR contracts NAS8-97195 and NAS8-98081.


A Highly Scalable Simple Camera Controller for the SAO Megacam

Prototyping of the massively parallel 72-channel SAO megacam has been completed and we are preparing the printed circuit boards for initial deployment.


The implementation of the San Diego State University Gen II CCD controller ( SDSU II ) at the Isaac Newton Group of Telescopes (ING).

In order to fully exploit new detectors, such as the EEV42, the ING is in the process of upgrading to the SDSU II CCD controller. A total of fifteen single CCD & mosaic cameras are to be updated. This paper presents the way in which the SDSU II CCD controller is being implemented at ING, the progress made and the experience gained.






Newer High speed devices

Hopefully will be an oral paper


A Flexible Controller for CCDs and Near IR Arrays


The array controller developed at Ohio State, and now in routine use on eleven telescopes with seven different detector types, is described. Detector

limited performance, 1 to 40 channels, modularity, hardware designed for mountaintop environments, and transparent transfer of FITS images to a range of hosts are key features.


A One-Dimensional Survey Mosaic

A design for a one dimensional mosaic of 1k by 3k CCDs is presented. The observing advantages of a one-dimensional array is described.

de Kat & Boulade

MegaCam, the next generation wide-field camera for CFHT

We are developing a new camera consisting of a mosaic of 40-44 thinned 2kx4k CCDs. We describe some parts of the system like the pulse tube for cooling down the mosaic without LN2 or any vibration, the low noise fast electronics for controlling 44 devices and reading 88 channels in 20s and so on.


The AAO2 CCD Controller Project and Two Years of LL CCD Observing Experience

The plans for the AAO's next generation CCD/IR detector controllers now in production will be described, as well as the AAOs experience with two Lincoln Lab CCID20s which have been in use now for 2 years.


The CFH12K First Light


To illustrate the capabilities of this new CFHT instrument, this poster presents a combination of simple diagrams describing the camera data handling (acquisition/processing/archive) and a set of color astronomical pictures from the CFH12K first light at the prime focus in January 1999. The overall performances of the camera are summarized.

Andersen, Michael

Customizing CCDs for fixed format high resolution spectrographs


A high resolution spectrograph, giving a fixed format echelle spectrum, offers the opportunity to optimize the different areas of the CCD for specific wavelength. It is shown that a slight modification of the conventional single layer anti-reflection coating may provide a major improvement in QE for such instruments, while at the same time minimizing problems with fringes and stray light from the CCD.


High Speed, high resolution camera for gamma bursts


The rapid telescope for the observation of transients objects ( TAROT-1) installed on the Calern plateau (near Nice) is meanly dedicated at the detection of the optical counterparts of cosmic g-ray bursts (GRB). TAROT is able to slew to any point in less than 3 s. The short GRB duration's impose a very short readout time. Typical exposures last from 1 sec. to 60 sec. or more. To meet the objective of reaching the 19th magnitude in 1 minute the total noise must be limited at 10 e-. In addition, it is often necessary to record many times an image during the prompt part of the optical transient. So we have fixed a readout time of 1 second for the full sensor without binning. We have chosen the Thomson CCD sensor TH7899M: it can be read fast enough with good performances in noise, through 4 channels. Therefore the readout frequency is 1 MHz. We have also a faster mode with a readout time of 500 milliseconds. The digital controller is made with 2 logic programmable circuits. One is in charge the phases signals, the other makes computations for the numeric CDS. The result is send to the computer via an optical fibbers link. The conversion is done by a high speed analog to digital 14 bits converter. We have taken a very great care on the preamplifier and amplifier design, particularly in settling time performances.

Fechner, Roth & Wolter

CCD Systems for PMAS


PMAS, the Potsdam Multiaperture Spectrophotometer, is an optical integral field instrument for the Calar Alto 3.5m telescope, currently under development at the Astrophysical Institute Potsdam. With kind permission of the ESO Optical Detector Group, ESO designs for the CCD detector heads and controllers have been employed. We will describe the current status of the project and report on the performance of the 2 CCD systems that are built into PMAS.


CCD Sub-pixel Centroiding Accuracy as a Function of TDI Clocking Technique.

A precision linear translation stage is used to move an EEV CCD42-80 CCD past a fixed light source simulating a stellar field. The image area is clocked in a standard line-prompted manner, or with equal time between clock phase transitions. The resultant sub-pixel centroiding accuracies, particularly along the scan axis, are compared.


A Shutter for BUSCA


Large CCD4s needs large shutters. So we've built a slit type shutter for precision photometry. It consists basically of two carbon fiber blades moving on linear ball bearings driven by stepper motors and tooth belt. The aperture is 110mm * 110mm. Short exposures are possible with a maximum error of less than 1 ms in the whole field. The Shutter will be demonstrated in action.


BUSCA: A simultaneous 4 colour camera system with 4kx4k CCDs.


BUSCA (for: Bonn University Simultaneous Camera) is an instrument for the Calar Alto 2.2m telescope. It is equipped with a set of dichroic filters to separate four wavelength bands and with four individual CCD systems, one for each color channel. We use the 4Kx4K 5 micron pixel CCD485(Lockheed Martin Fairchild Systems) to cover the four focal planes of 12' x 12' (60mm x 60mm). Three front side devices are in operation since Feb. 99. The presentation gives an overview of the instrument. The operation and characteristics of the 4K devices are discussed in detail.


How well can CCDs detect clouds in a dark sky?


An all sky cloud camera is of particular interest to astronomical observatories on moonless nights when thin clouds are difficult to assess reliably by eye. The need becomes more general and more pressing when observations are scheduled dynamically and/or telescopes are operated remotely. Thermal IR cameras have been shown to detect clouds very effectively but they are still expensive, and vulnerable to dust accumulating on their warm optics. Initial experiments indicate that a very useful and much cheaper cloud monitor can be constructed from commercially available CCDs and mass produced lenses. Time lapse movies showing clouds and air glow and some splendid dark skies will be presented along with a short discussion of design trade-offs.


Using KAF-4201 CCDs for astronomy.

Two cameras using the Kodak KAF-4201 CCD have recently been built and commissioned on astronomical telescopes. The suitability of this CCD for astronomy is evaluated from laboratory and sky data.


To be supplied

To be supplied